DSA · Theory

Construct BST from its given level order traversal

Theory

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Construct BST from its given level order traversal

Construct BST from its given level order traversal is a DSA topic. In plain words you use it for folder on disk in a file explorer. Don’t start with a slogan — start with that picture.

Smallest example: left < root < right. Type it, run it, and say what you see. If you can do that from memory, you know Construct BST from its given level order traversal.

From the example next to this theory: Construct BST from its given level order traversal — bST invariant: left < node < right — enables log-time search when balanced.

Trap — unbalanced BST becoming a list. Fix that before you talk about advanced DSA.

Viva — what is Construct BST from its given level order traversal? Then show left < root < right. Then name the trap.

Diagram

Exam tip

What is Construct BST from its given level order traversal? Show this: left < root < right. Trap: unbalanced BST becoming a list.

Example

class Node:
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None

def insert(root, val):
    if root is None:
        return Node(val)
    if val < root.val:
        root.left = insert(root.left, val)
    elif val > root.val:
        root.right = insert(root.right, val)
    return root

root = None
for v in [5, 2, 7, 1]:
    root = insert(root, v)
print(root.val, root.left.val, root.right.val)

Construct BST from its given level order traversal — bST invariant: left < node < right — enables log-time search when balanced.

Short notes

DefConstruct BST from its given level order traversal — folder on disk in a file explorer.
Ruleleft < root < right
Trapunbalanced BST becoming a list
Usea file explorer

class Node: def __init__(self, val): self.val = val self.left = None self.right = None def insert(root, val): if root is None: return Node(val) if val < root.val: root.left = insert(root.left, val) elif val > root.val: root.right = insert(root.right, val) return root root = None for v in [5, 2, 7, 1]: root = insert(root, v) print(root.val, root.left.val, root.right.val)

Construct BST from its given level order traversal

Example

Short notes

Questions

Construct BST from its given level order traversal

Example

Short notes

Questions